Solar Panels and Electric Cars: Can I Use Solar to Charge My Vehicle?

| 2/5/2016 10:11:00 AM

Tags: solar power, electric vehicles, home energy, batteries, Vikram Aggarwal, Massachusetts,
solar and electric cars

Solar panels and electric cars are a match made in heaven ­– when you install a solar energy system on your home, you can use it to both power your home and charge your electric car for emissions-free transportation. The cost of solar is falling rapidly, and companies from Tesla to Nissan are manufacturing electric cars for your daily use. Now, the ability to install a solar PV system large enough to power both your home and your car is an option within reach. But even with incentives and rebates available for both technologies, most homeowners still can’t afford to install solar and buy an electric car at the same time. Luckily, it’s easy to install a solar energy system today that takes your future electricity consumption into account, if you take a few additional factors into consideration.

How Much Electricity Does an Electric Car Use?

Before you can make a decision on the size of your solar energy system, you need to determine how much electricity your car will use in the future. In addition to helping you size your solar energy system, knowing your electric car’s mileage rating can help you quantify the amount that you’re saving by switching to an electric vehicle.

Since electric cars don’t run on gasoline, the EPA rates them based on how many kilowatt-hours (kWh) it takes for the car to drive 100 miles, which they convert to a “miles-per-gallon equivalent” (MPGe). You can use U.S. Dept. of Energy's Fuel Economy website to find and compare the kWh/100 miles and MPGe ratings for all of the electric vehicles on the market in the United States.

Once you know EPA’s fuel economy rating for your chosen vehicle, you can easily calculate how much extra solar electricity you’ll need to charge your car. Here’s an example: the 2014 Nissan Leaf, an all-electric vehicle, has a combined fuel economy rating of 30 kWh/100 miles – this means the Leaf requires 30 kWh of electricity to drive 100 miles. If you drive 25 miles on an average day, that means you’re using approximately 7.5 kWh of electricity per day – or just over 2,700 kWh of electricity in a given year. This is the “extra” amount of electricity you’ll need your solar energy system to produce.

Armed with this information, you can work with your solar installer to design a solar panel system that will generate sufficient power to cover both your home and your electric car. But if you’re not ready to make the investment in both at the same time, you’ll need to install a solar PV system that can grow as your electricity use increases. 

How to Size Your Solar Energy System for Future Use

First things first: don’t put off going solar just because you might want to get a bigger system in the future. If you wait to install solar, you could miss out on state and local financial incentives – plus, you’ll have to continue paying for electricity from your utility every month. By sizing your solar energy system for future usage and ensuring your system is “add-on friendly”, it’s easy to find an option that generates enough electricity to power your home today and can charge your electric car in the future. Here’s how to do it:

12/5/2016 10:01:40 PM

Does anybody know if solar panels can actually power an EV charger? My condo complex is looking into possibly putting a charger in a common area next to a stretch of individual garages and wondered if putting panels on the garages could supply power to the EV charger. I am just getting started with this research and don't have a lot of information.

2/6/2016 1:04:42 PM

The combination of solar panels and electric vehicles is a very powerful one. A good percentage of total greenhouse gases comes from the residential/commercial and transportation sectors. So a homeowner can make significantly lower his or her carbon footprint by going solar and buying an EV. An increasing amount of people will be using their solar panel systems to charge their vehicles. It just makes good sense. Nick Tedesco

2/5/2016 2:31:23 PM

Or to look at it another way: Your EV will likely have a dash indication of miles/kWh. For example my Leaf travels about 4.5 miles/kWh. Then look at miles driven per year (often dictated by your lease). In my case the answer is 12,000 mi/yr. Then divide miles/yr. by miles/kWh. In my case it's 12,000/4.5 = 2,667 kWh consumed in a year. Now there are websites like where you can enter this information along with your zip code and learn the size of solar array you need to essentially erase your car's impact on the grid. Then it's a few quick calls for a quote. In many areas of the country this works out to be a small system that covers an area of a one car garage and won't set you back much green. Remember to have a grid tied system as you will want to charge at night. At the end of each year if the solar power generated is greater than or equal to the power you car burns, you have a solar powered car even if you borrow some electrons during the night and pay them back the next day.

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